Best overall: Dometic OEM Flush Ball Seal — it’s the genuine Dometic part, made from OEM materials the listing says resist chemicals and keep the flush ball moving without stickiness. It fits Dometic and Sealand 300 and 400 series toilets.
Best first-time buyer: Dometic 300/310/320 Seal Kit — a two-pack with a “THIS SIDE UP” logo, no tools, and the listing says about a five-minute press-in job with no toilet disassembly.
Best for hard use: Dometic Sealand VacuFlush Seal — a silicone bowl seal plus a heavy-duty PTFE disk with grooves, and the grooves line up with the black seal so it won’t shift while you install it.
The rest of this guide walks through each toilet seal, who it fits, and what to check before you order a rubber replacement.
How We Picked
We compared the Amazon listings for RV toilet seals and rubber gaskets.
A flush ball seal, a floor flange seal, and a blade seal do different work, and a buyer should know which one is leaking before ordering.
All 10 products side by side — scroll sideways to see every column.
| Top Pick | Runner-Up | Best for 2001+ Toilets | Best for Thetford Style | Best Blade Seal | Best for Floor Leaks | Best for Mansfield Models | Best for VacuFlush | Best for Gravity Flush | Best for Spare Kits | |
| Preview |  |  |  |  |  |  |  |  |  |  |
|---|---|---|---|---|---|---|---|---|---|---|
| Product | Dometic OEM Flush Ball Seal | Dometic 385311658 Flush Ball Seal | Dometic OEM Rubber Seal Kit | Thetford 34120 Waste Ball Seal | Thetford 33027 Aqua Magic Seal | Thetford 33239 Closet Flange Seal | Dometic 385316140 Seal Kit | Dometic Sealand VacuFlush Seal | SEAFLO SFTRK-005 Gasket Kit | Dometic 300/310/320 Seal Kit |
| Brand | Dometic | NZRAQK | Dometic | Oyviny | Thetford | Thetford | Oyviny | KPALAG | SEAFLO | TeegRoow |
| Best for | Best Overall | Runner-Up | Best for 2001+ Toilets | Best for Thetford Style | Best Blade Seal | Best for Floor Leaks | Best for Mansfield Models | Best for VacuFlush | Best for Gravity Flush | Best for Spare Kits |
| The listing says | OEM materials for long-lasting performance Restores seal, stops odors and bowl leakage | Fixes odor and water leakage from broken gasket Fits Dometic 300/ 310/ 320 RV | Dometic genuine part, OEM quality fit Replaces worn seals and stops odors | 34120 waste ball seal stops odor and leakage Replaces 34120 & 12524 toilet seal part | Made for Thetford Aqua-Magic IV High and Low Hand Flush High-grade blade seal for maximized performance | Closet flange for Thetford toilets Universal fit | Fits Dometic, SealLand, VacuFlush, Mansfield models 506, 510, 511 H, 547, 548, 706, 709, 7 Not fit for 300, 310, 320 series | Bowl seal without drain holes has grooved white ring Replaces 385311462 and 385310677 | Model Number: SFTRK-005 Color: Black | Rubber seal kit fixes water leakage and odor Fits Dometic 300/310/320 models (Part #385311658) |
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1. Dometic Genuine OEM Flush Ball Seal Kit
Best for: Dometic and Sealand 300/400 owners
This is the genuine Dometic flush ball seal kit, part 385311658. The listing says it’s built from OEM materials for chemical resistance and long life. It’s made to restore the seal at the flush ball, which is the spot that lets odors up and water down when the rubber wears out.
The practical value of the OEM material claim is chemical resistance. The listing also says it allows the flush ball to move freely without stickiness.
The compatibility list is narrow on purpose. It covers Dometic and Sealand 300 and 400 series toilets. If your toilet is a 2001-or-newer model or a VacuFlush, this isn’t the one for you — check the other Dometic picks below before ordering.
Pros
- Genuine Dometic OEM part, not a copy
- Stated chemical resistance for toilet treatments
- Fits Dometic and Sealand 300/400 series
Cons
- Only fits 300 and 400 series toilets
- Kit covers the flush ball seal only
2. Dometic 385311658 Flush Ball Seal
Best for: Buyers who want a spare on hand
This is a two-pack of flush ball gaskets for Dometic 300, 310, and 320 toilets, replacing part 385311658. The rubber blend is molded from original equipment tooling.
Two seals in one box changes how you plan the job. You can do the repair now and keep the second one for the next time the bowl stops holding water, which is a real convenience on a part that wears. The listing is also clear about what it doesn’t fit: models 210 and 510, and anything not named.
Installation is spelled out step by step — shut off the water, lift out the old flush ball without pulling the toilet, press the new seal in with the “THIS SIDE UP” marking facing up, then check for leaks. The seller states a 30-day return and exchange policy.
Pros
- Everything you need for a full replacement comes in the pack
- Stated 30-day return window
- Doesn’t require toilet disassembly
Cons
- Doesn’t fit 210 or 510 models
- Only covers 300/310/320 toilets
3. Genuine Dometic OEM Rubber Toilet Seal Kit
Best for: Owners of 2001 and newer Dometic toilets
This is the genuine Dometic rubber toilet seal kit, part 385311462, for Dometic toilets built in 2001 and newer. The listing frames it as OEM quality fit and finish, and as a routine service part — the kind of thing you replace on a schedule rather than after a failure.
That framing is the honest way to read it. This is a maintenance item, and the listing says it replaces worn seals and stops odors. If your bowl holds water but you’re chasing a faint smell, a worn seal is a common cause and this is the part that addresses it.
The catch is the fit window. “2001 and newer” is a broad statement, and the listing doesn’t break it down by series the way the flush ball seal does. Confirm your model number against the part before you order, because the listing states the seal fits only the models it names.
Pros
- Genuine Dometic OEM part
- Listed for odor control and routine service
- Fits Dometic toilets 2001 and newer
Cons
- Fit stated by year, not by model series
- No installation steps listed
4. Thetford 34120 Waste Ball Seal
Best for: Thetford Aqua-Magic Style owners
This is a 34120 waste ball seal kit for Thetford Aqua-Magic Style Plus, Style Lite, Style II, and Residence toilets. It replaces both the 34120 waste seal and the 12524 floor base seal, so it covers two leak points in one box.
The dimensions are printed, which is unusual and useful. The 12524 floor base seal is 4.8 inches outer diameter, 3.3 inches inner, and 0.5 inch thick. The waste seal is 4 inches outer, 2.7 inches inner, and 0.4 inch thick. Measure your old parts against those numbers before ordering — that’s the fastest way to confirm you have the right kit.
Installation is the standard routine: water off, old flush seal and floor seal out, edges cleaned, new ones in, then check for leaks.
Pros
- Covers both waste seal and floor seal
- Printed dimensions for easy checking
- Silicone and foam rubber construction
Cons
- Only fits Thetford Style series toilets
- More than one part has to seat correctly, not just a single piece
5. Thetford 33027 Aqua Magic IV High and Low Blade Seal
Best for: Thetford Aqua-Magic IV owners
This is the Thetford 33027 blade seal, made only for Aqua-Magic IV High and Low hand flush units. The listing says it’s manufactured exclusively for those models, which is the whole point — a blade seal has to match the blade it rides against.
The listing describes a structured, precisely manufactured part built through a series of careful processes. That’s marketing language, but the compatibility claim underneath it’s specific and checkable: Aqua-Magic IV High and Low hand flush only. If that’s your toilet, this is the correct blade seal.
Read the contents line carefully. The listing says it includes the blade seal only. Nothing else comes in the box, so if your floor seal or flange is also worn, you’ll need those separately. This is a single-part repair, and it’s the right one only if the blade seal is what’s failing.
Pros
- Made exclusively for Aqua-Magic IV units
- Correct blade seal for High and Low flush
- Single-part replacement
Cons
- Includes the blade seal only
- No other components in the box
6. Thetford 33239 Closet Flange Seal
Best for: Thetford owners chasing a floor leak
This is the Thetford 33239 closet flange seal in gray. It replaces part 02125, and 33239 is the current part number. The listing describes it as a closet flange for Thetford toilets with universal fit.
The job this does is different from everything else on this list. A flush ball seal handles the bowl; a closet flange seal handles the joint at the floor. If water is pooling at the base of the toilet rather than sitting in the bowl, you’re looking at the flange, not the ball.
The listing is short. It gives the part number, the part it replaces, and the fit type, and that’s about it. There are no dimensions and no installation steps. That’s not a fault in the part — it just means you should confirm the number against your toilet’s manual before ordering rather than relying on the listing to walk you through it.
Pros
- Replaces Thetford part 02125
- Current part number 33239
- Universal fit for Thetford toilets
Cons
- No dimensions listed
- No installation steps listed
7. Dometic 385316140 Seal Kit
Best for: VacuFlush, Sealand, and Mansfield owners
This is a flush seal replacement kit with parts 385316140 and 385311462, for Dometic, Sealand, VacuFlush, and Mansfield toilets. The compatibility list is the longest here, covering 506, 510, 511H, 547, 548, 706 through 749, 806 through 848, 1147, 1148, 2010, 2011, 5006, and the 5047 to 5049 group, plus EcoVac 146 to 149 and a long run of VacuFlush numbers.
The seals go in, in a set order. Getting that order wrong is the mistake to avoid, because the stack is what makes the seal.
The listing is explicit about what it doesn’t fit: 300, 310, and 320 series toilets, and it notes the seals don’t include overflow holes. If your toilet is one of those three series, this kit is the wrong one — take the 385311658 gaskets instead. The material is silicone rubber, stated to resist deforming or cracking.
Pros
- Very long compatibility list
- A full set of seals is included in the kit
- Silicone rubber construction
Cons
- Not for the 300, 310, or 320 series
- Seals have no overflow holes
8. Dometic Sealand VacuFlush Seal
Best for: Dometic VacuFlush and gravity owners
This is a bowl seal kit with no drain holes, replacing parts 385311462 and 385310677, for Dometic and Sealand toilets. The compatibility list runs from 110 and 111 up through 210, 510, 511, 511H, 506+, 508+, 509+, 547+, 548+, 568, 706 through 749, 711-M28, 711-98C, 712-TM09, 806 through 848, 910, 911, 1147, 1148, 2010, 2011, 5006, and 5047 to 5049, plus EcoVac 146 to 149 and VacuFlush 168 through 5149.
The design detail is the reason to pick this one. The white seal ring has grooves that line up with the black seal, and the listing says that alignment stops the seal from shifting during installation. Anyone who has fought a seal that slid out of place while seating it will understand what that’s worth.
Materials are silicone rubber for the black gasket and a heavy-duty PTFE disk with grooves, described as hard and wear resistant. As with the other wide-fit Dometic kits, it isn’t compatible with 300, 310, or 320 series toilets. Installation steps are provided in the images at the bottom of the listing page.
Pros
- Grooved design resists shifting on install
- Silicone rubber plus PTFE disk
- Wide VacuFlush and gravity feed fit
Cons
- Not for 300, 310, or 320 series
- Installation steps only in listing images
9. SEAFLO RV Toilet Gasket Flange Seal Kit (SFTRK-005)
Best for: SEAFLO gravity flush toilet owners
This is the SEAFLO SFTRK-005 gasket flange seal kit in black, for SEAFLO gravity flush RV toilets — models SFRTPH-01-01, SFRTPH-01-02, and SFRTPH-02-01. The dimensions are printed: 4 inches outer diameter and 2.75 inches inner diameter.
That’s the tightest compatibility list on this page, and it’s also the clearest. There’s no guessing here. If you own one of those three SEAFLO models, this kit is built for your toilet and nothing else. If you own anything else, it isn’t.
The listing says the gasket is made from premium materials for a long service life in demanding RV environments, and that it’s specifically designed to address leakage in SEAFLO gravity flush units. It’s a flange seal, so it handles the floor joint rather than the bowl.
Pros
- Printed 4-inch and 2.75-inch dimensions
- Made specifically for SEAFLO gravity flush
- Black gasket flange seal
Cons
- Fits only three SEAFLO models
- No return window stated
10. Dometic 300/310/320 Seal Kit
Best for: First-timers who want a spare
This is a two-pack of seal replacement kits for Dometic 300, 310, and 320 toilets, part 385311658. The seals are made of wear-resistant rubber and designed using original molds to fit perfectly and seal against leaks.
The reason this suits a first-timer is the installation description. There’s a “THIS SIDE UP” logo to tell you which way the seal faces, no tools are needed, and the listing calls it a five-minute job — pull the old gasket and press the new one in, without disassembling the toilet. For someone who has never been near an RV toilet seal, that orientation mark removes the most common way to get it wrong.
The two-pack matters for the same buyer. If the first attempt doesn’t seat right, you’re not stuck waiting on another order. The listing says the seals restore a watertight connection and prevent odors and leaks.
Pros
- A complete set of kits comes in the pack
- “THIS SIDE UP” mark for correct fit
- No tools and no disassembly stated
Cons
- Only fits 300, 310, and 320 models
- Five-minute install is the seller’s claim
How to Choose in Sixty Seconds
Which seal do I actually need?
Match the seal to where the problem shows up. Water sitting in the bowl that slowly drains away points to the flush ball seal — that’s the Dometic OEM Flush Ball Seal or the Dometic 385311658 Flush Ball Seal. Water pooling at the base of the toilet points to the floor joint, which is the Thetford 33239 Closet Flange Seal or the SEAFLO SFTRK-005 Gasket Kit. A smell with no visible water usually means a worn bowl seal, like the Dometic OEM Rubber Seal Kit. Get the location right first, then pick the part.
What should I check before I order?
Three things, in this order. First, your toilet’s model number — not the brand, the model. Second, the part number the listing says it replaces, and whether that matches the part you’re pulling out. Third, what’s in the box, because some kits include one seal and some include two. The Thetford 34120 kit covers both the waste seal and the floor seal, while the Thetford 33027 includes the blade seal only. Checking those three things takes two minutes and prevents the most common return.
Do I need the OEM part or is a replacement fine?
Both work, and the listings split the difference for you. The genuine Dometic parts state OEM materials and OEM fit and finish. The replacement kits state their own materials — silicone rubber, foam rubber, PTFE disks — and several name the exact part number they replace. What matters more than the badge is whether the listing names your toilet model and the part number it replaces. A replacement that lists your model clearly is a safer buy than a genuine part listed for a different series.
Related guides
Frequently Asked Questions
How do I know which seal is leaking?
If the bowl holds water when you fill it and then slowly empties, the flush ball seal is the one to replace — that’s the Dometic OEM Flush Ball Seal or the Dometic 385311658 Flush Ball Seal. If water shows up around the base on the floor, the floor joint is failing, and you want a flange seal like the Thetford 33239 or the SEAFLO SFTRK-005.
What does replacing one of these actually involve?
Less than most people expect. The Dometic 300/310/320 Seal Kit states no tools are needed and calls it a five-minute job, with a “THIS SIDE UP” mark to show the correct orientation. The Dometic 385316140 Seal Kit is the exception — it needs two seals stacked in a set order, thick one first.
What goes wrong first with an RV toilet seal?
Wear at the sealing edge, and it usually shows up as a bowl that won’t hold water. The listings describe this the same way: a broken or worn gasket causes odor and leakage. Materials are chosen to slow it down — silicone rubber stated not to deform or crack, PTFE disks for wear resistance, OEM rubber for chemical resistance against toilet treatments.
Is the simplest seal on this list enough?
It depends on your toilet, not on the seal. The SEAFLO SFTRK-005 Gasket Kit is made for exactly three SEAFLO gravity flush models and nothing else. If you own a Dometic 300, 310, or 320, the Dometic 300/310/320 Seal Kit covers it with a spare included.
Closing
For most RV owners, the Dometic OEM Flush Ball Seal is the one to start with. It’s the genuine part, it’s built for chemical resistance, and it covers the 300 and 400 series toilets where flush ball seals fail most often. If you want a spare in the drawer and an easier install, the Dometic 300/310/320 Seal Kit gets you two seals with an orientation mark that takes the guesswork out. Before you order anything, write down your toilet’s model number and the part number on the old seal, then match both against the listing.
